The present invention relates to a reading device for a dobby machine.
There is known a reading device in which a reading lever is adapted to rotate and shift between two positions around a single shaft according to whether a peg on a rotating cylinder is present. A retaining hook is pivotably mounted on said shaft and connected to the reeding lever through a spring. The reeding lever and retaining hook are integrally rotatable. The retaining hook is adapted to take engaged and disengaged positions with respect to a periodically pivoting movable hook.
More particularly, an intermediate position of a balk which pivotally supports movable hooks at both ends thereof is rotatably supported by a fore end portion of a balk lever which is pivotable around a fixed shaft independent of the shaft of the reading lever. The movable hooks at both ends of the balk are adapted to move with the pivotal motion of the balk between engaged and disengaged positions with respect to the retaining hook by being pushed with pushing bars which are adapted to reciprocate in opposite directions alternately at a 180.degree. shift.
Therefore, when the movable hook on one side of the balk is pushed by a pushing bar and reaches the position of engagement with the retaining hook while the retaining hook integral with the reading lever displaced in abutment with the peg on the cylinder is located in the engaged position, the retaining hook is slightly moved forcibly by the movable hook against the force of the spring connected to the reading lever, so that the movable hook and the retaining hook come into engagement with each other. Further, as the movable hook portion on the opposite side is pushed by a pushing bar, the balk lever turns around the fixed shaft and a heald frame ascends or descends through a jack lever connected to the said balk lever and a wire rope, whereby a warp shedding is performed.
In the above dobby machine, the reading lever and the retaining hook are supported coaxially rotably and a spring is connected between the reeding lever and the retaining hook so that the reading lever and the retaining hook are integrally rotatable while the reading lever is in pressure contact with a stopper on the retaining hook. Further, the retaining hook is urged away from the movable hook by means of a spring disposed between the retaining hook and another fixed pin. This urging force also serves to urge the reading lever against the peg on the cylinder.
In such reading device, when the reading lever is displaced by the peg on the cylinder, the retaining hook turns at the same angle as the turning angle of the reading lever; that is, the angular velocity of the reading lever and that of the retaining hook are equal. Therefore, the turning speed of the retaining hook from its disengaged to engaged position with respect to the movable hook is constant, so at a high speed, e.g. 500-1000 r.p.m., of the dobby machine, there may occur shock or vibration and out-of-engagement with the movable hook when the retaining hook reaches its position of engagement, or sudden movement and stop may cause a crack of the weaker member at the portion of abutment between the reading lever and the retaining hook.
Further, as to the urging force of the reading lever against the peg, the force of an exclusive-use spring acts directly as such urging force as previously noted, so the extension of the spring with displacement of the reading lever directly increases the load to the peg, thus accelerating wear of the peg surface. Besides, with speed-up of the dobby, the peg strongly abuts and displaces the reading lever, so there may occur breakage due to impact fatigue of the weaker member, thus shortening the service life.
It is the object of the present invention to solve the above-mentioned problems.